The present invention relates to a system for providing chilled and super-atmospheric air charge to an engine on a preferential basis.
Engine designers have devised a potpourri of systems for increasing the density and decreasing the temperature of the air charge entering an internal combustion engine.
For ordinary driving, it is desirable, on only a very infrequent basis, to operate the engine at its highest possible output. Thus, it is not desirable or necessary, from the standpoint of cost, fuel consumption, or weight, to have a system, which is capable of providing densified and chilled air to the engine on a continuous basis in a quantity sufficient to support the engine""s maximum output.
It is known to provide densifying and even chilling on a basis in which the densification and chilling will operate on a continued basis, but such systems, alluded to above, are hampered by excess cost, weight, and power consumption.
A system according to the present invention overcomes the disadvantages of prior densification and chilling systems while providing excellent throttle response for infrequent accelerations by providing alternative pathways for air to enter the engine""s air supply plenum. Thus, during normal operation, the air will enter into the unchilled passageway, allowing the chilling apparatus to be pulled down to a very low temperature so as to provide a transient but very high level of densification and charge cooling. Because the densification apparatus does not operate continuously, power consumption of the apparatus is low. Moreover, because chilling is not required to operate continuously, a very high level of chilling is available on an intermittent basis, which is consistent with usage of such system for normal driving.
A charge air management system for an automotive engine includes an air intake plenum for furnishing air to the engine, a first duct for furnishing air to the intake plenum, and a second duct for furnishing air to the intake plenum. A charge booster increases the quantity of air entering the plenum from the second duct. An intercooler removes heat from air flowing through at least the second duct. Finally, a splitter valve controls the relative proportion of air flowing into the plenum from the first and second ducts.
According to the present invention, a charge booster may comprise a supercharger or an exhaust driven turbocharger. If a supercharger is used, it may be driven by a clutched drive.
According to another aspect of the present invention, the splitter valve is preferably operated such that the plenum is furnished with air flowing through the first duct at relatively lower loads and with air flowing through the second duct at relatively higher loads.
Liquid coolant is chilled by the air-to-liquid heat exchanger only if the temperature of the liquid coolant leaving the intercooler exceeds the ambient air temperature by an amount greater than a predetermined threshold.
The refrigerated fluid, which chills the liquid coolant in the liquid-to-liquid heat exchanger, comprises refrigerant fluid flowing in a vehicle air conditioning system. The air conditioning system is called upon to furnish the refrigerant fluid only if the demand placed upon the air conditioning system is less than a predetermined threshold. In other words, if the vehicle occupants demand a high level of air conditioning service, refrigerant fluid will not be allowed to flow to the liquid-to-liquid heat exchanger.
As noted above, the flow of charge air through the first and second ducts is controlled by a splitter valve, which is itself controlled so as to send most of the air into the plenum through the second duct in the event that the throttle associated with the engine is opened at a rate exceeding a threshold opening rate. Similarly, the splitter valve is controlled so as to send most of the air into the plenum through the second duct in the event that the airflow through the engine exceeds a threshold airflow rate.
According to another aspect of the present invention, a method for operating an automotive engine having a charge air management system for furnishing air to an air intake plenum associated with the engine includes the steps of providing air to the plenum through an uncooled duct during normal operation at lower power levels, providing coolant to a cooled duct during normal operation so as to chill the cooled duct when air is being provided to the plenum through the uncooled duct, and providing air to the plenum through the cooled duct during operation of the engine at higher power levels.